Industrial controllers are special-purpose computers utilized for controlling industrial processes, manufacturing equipment, and other factory automation, such as data collection or networked systems. At the core of the industrial control system, is a logic processor such as a Programmable Logic Controller (PLC) or PC-based controller. Programmable Logic Controllers for instance, are programmed by systems designers to operate manufacturing processes via user-designed logic programs or user programs. The user programs are stored in memory and generally executed by the PLC in a sequential manner although instruction jumping, looping and interrupt routines, for example, are also common. Associated with the user program are a plurality of memory elements or variables that provide dynamics to PLC operations and programs. Differences in PLCs are typically dependent on the number of Input/Output (I/O) they can process, amount of memory, number and type of instructions, and speed of the PLC central processing unit (CPU).
Additionally, electronic operator interfaces (EOI) are enhanced computer display devices that can include a plurality of operator input means, such as touch screens, keypads, and so forth. EOIs are therefore capable of both displaying information, and receiving inputs from operators. Typically, EOIS are in communication with one or more industrial controllers, and provide graphical and/or text displays of the control system and statuses for various associated components. Therefore, EOIs enable operators to interact with control systems by displaying control system data and accepting operator inputs.
In the past, manufacturing equipment was often controlled with large and complex circuitry that included enormous amounts of relay logic. These specialized circuits were difficult to update and/or modify, and may have only been understood by a small group of users outside of the designers. Modern industrial controllers allow for fast and efficient creation of control logic that can be generated, understood, and/or modified by a much larger number of potential users. However, the increased ease of use and access can also lead to the existence of multiple versions of the same control logic within a project or organization.
When there are multiple versions of the same control logic present among a group of users, a situation can arise where none of the users is aware of, or has access to, the most recent version. Consequently, one user may overwrite another user's updates, because the first user believed that he/she was working on the most recent version of the control logic. In addition, if the only trusted version is stored on the industrial controller, and the controller fails, then numerous updates and modifications may be lost.